1. Field of the Invention
The present invention relates to a transmission shaft set and, more particularly, to a transmission shaft set having the properties of high toughness and high friction resisting power that produces low noise, dissipates heat. The shaft and axle bush of the transmission set are respectively made of zirconia-modified material of high toughness and zirconia-modified material of high hardness to achieve a long service life.
2. Description of the Related Art
The transmission shaft set of a regular fan is generally comprised of a high lubricating bronze axle bush and a stainless steel shaft. The porous structure of a bronze axle bush effectively holds grease, providing a satisfactory lubricating function. However, due to high heat expansion coefficient (4xcx9c5 times over ceramics), a bronze axle bush deforms quickly when operated at a high speed. Further, because of low hardness (below Hv500), a bronze axle bush wears quickly with use. The service life of a bronze axle bush is about 10000 hours. When a ball bearing is used in a transmission shaft set to support the shaft instead of an axle bush, the service life of the transmission shaft set can be prolonged to about 50000xcx9c60000 hours, however it produces vibration and high noise during operation. Recently, precision ceramic materials have been intensively used for making ball bearings or axle bushes instead of bronze. A precision ceramic ball bearing or axle bush does not deform easily when hot, however it is not suitable for high speed or high torque application.
The present invention has been accomplished to provide a transmission shaft set, which eliminates the aforesaid drawbacks. It is therefore the main object of the present invention to provide a transmission shaft set, which produces low noise and low friction resistance during operation. It is another object of the present invention to provide a transmission shaft set, which dissipates heat quickly during operation. It is still another object of the present invention to provide a transmission shaft set, which does not expand easily when hot. It is still another object of the present invention to provide a transmission shaft set, which is practical for high speed and high torque application. To achieve these and other objects and according to one aspect of the present invention, the shaft and the axle bush of the transmission shaft set are respectively made of material of high toughness and material of high harness such that the hardness difference between the shaft and the axle bush is about Hv100xcx9cHv400, and the hardness of the axle bush is higher than the shaft. According to another aspect of the present invention, a lubricant is applied to the gap in the contact area between the shaft and the axle bush to minimize operating noise.